diff --git a/test_book/src/individual/heading.md b/test_book/src/individual/heading.md
index df96d74c..f9f4d5b2 100644
--- a/test_book/src/individual/heading.md
+++ b/test_book/src/individual/heading.md
@@ -13,3 +13,9 @@
 ##### Really Small Heading
 
 ###### Is it even a heading anymore - heading
+
+## Custom id {#example-id}
+
+## Custom class {.class1 .class2}
+
+## Both id and class {#example-id2 .class1 .class2}